Bitmart: fetchOHLCV, add swap support
Bitmart: fetchOHLCV, add swap support

Added swap support to fetchOHLCV:
```
node examples/js/cli bitmart fetchOHLCV BTC/USDT:USDT '1m' 1665002338101 3
```
```
bitmart.fetchOHLCV (BTC/USDT:USDT, 1m, 1665002338101, 3)
2022-10-05T23:38:25.294Z iteration 0 passed in 931 ms

1665002341000 | 20091.4 | 20099.6 | 20089.9 | 20098.9 | 16214
1665002401000 | 20098.9 |   20099 | 20085.2 |   20090 | 10194
1665002461000 | 20085.6 | 20085.6 | 20080.4 | 20085.5 | 26062
3 objects
2022-10-05T23:38:25.294Z iteration 1 passed in 931 ms
```

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